#include <iostream>
using namespace std;

int main() {
    string s1, s2;
    string s;
    int n;
    cin >> n;
    cin >> s1 >> s2;
    int prev1 = -1, prev2 = -1;
    int ret = 0x3f3f3f3f;
    for (int i = 0; i < n; i++) {
        cin >> s;
        if (s == s1) {
            if (prev2 != -1) {
                ret = min(ret, i - prev2);
            }
            prev1 = i;
        }
        else if (s == s2) {
            if (prev1 != -1) {
                ret = min(ret, i - prev1);
            }
            prev2 = i;
        }
    }
    if (ret == 0x3f3f3f3f) {
        cout << -1 << endl;
    }
    else cout << ret << endl;
    return 0;
}